The present invention relates to a broadcasting control system and broadcasting control method in an ATM (Asynchronous Transfer Mode) ring network.
Conventionally, in an ATM ring network system, a plurality of nodes (#1 to #n) 2-1 to 2-n are connected into a ring shape, as shown in FIG. 4. In this arrangement, when a control user cell (to be referred to as a cell hereinafter) B is sent from the node 2-1, each of the nodes 2-2 to 2-n generates one response cell C in response to the cell B, so the number of response cells C increases toward the downstream.
Each of the above-described response cells C has a No (identification data) C1 of itself, e.g., a node No or VPI (Virtual Path Identifier) value in the payload, as shown in FIG. 6. The node 2-1 as a parent control node confirms the response states of the nodes 2-2 to 2-n on the basis of response data C2 in the payload.
FIG. 5 shows each of the nodes 2-1 to 2-n. Referring to FIG. 5, each of the nodes 2-2 to 2-n comprises an ATM switch (ATM SW) 21, a user cell receiving section 22 for receiving a cell branched from the ATM switch 21, a user cell transmitting section 23 for transmitting a cell through the ATM switch 21, and an MPU (Micro Processing Unit) 24 for transmitting response data to the user cell transmitting section 23 on the basis of control data output from the user cell receiving section 22. Reference numeral 201 denotes an upstream transmission line; and 202, a downstream transmission line.
When an ATM cell containing control data is broadcast from the node 2-1 for control, the ATM switch 21 in each of the nodes 2-2 to 2-n branches a cell. In addition, in each of the nodes 2-2 to 2-n, an ATM cell containing response data generated by the user cell transmitting section 23 is sent to the node 2-1 through the ATM switch 21.
In the above-described conventional ATM ring network system, since n-1 response cells C as shown in FIG. 6 are almost simultaneously generated for one broadcasting from a node, the user cell receiving section of each node is required to have high processing performance. For this reason, the ATM ring network system itself becomes uneconomical.
For example, the ITU recommendations I.630 are defined for ATM switching as recommendations for a 1:1 system. However, a 1:n system is a subject for future examination and has not been standardized yet.